msem-instigator

Target player can't cast spells this turn.
Fabled {2}{W}{U} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that player.)

Creatures you control get +1/+1 until end of turn. Merfolk you control get an additional +1/+1 until end of turn.

Creatures you control attacking causes their death knell to trigger.
Death knell — Indomitable Spirit gets +2/+2 and gains trample until end of turn. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)

You may sacrifice a land. If you do, search your library for a land card, put that card onto the battlefield, then shuffle.
Inscribe {3}{G} ({3}{G}: Exile this card from your hand inscribed on a creature you control. Whenever that creature attacks, its controller may cast a copy of the inscribed card without paying its mana cost. Inscribe only as a sorcery.)

Whenever you cast an instant or sorcery spell, upgrade Error Exploiter. (Give it one of the listed counters it doesn't already have.)
• +1/+1
• Flying
• Hexproof

Deathtouch
Heretic (Whenever you cast a spell that doesn't share a color with this creature, it gets +1/+1 until end of turn.)

Whenever Ravencaller or another creature enters from your graveyard, create a 1/1 blue Bird creature token with flying.

Flash
Flying
When Gale Conjurant enters, return target spell to its owner's hand if its mana value is less than or equal to the number of creatures in Gale Conjurant's pack. (Two or more creatures you control with equal power are in a pack.)

This creature has trample as long as there are four or more -1/-1 counters among creatures.
{3}{B}: Put a -1/-1 counter on target creature.

Target creature gets +X/+X until end of turn.
Fabled {X}{R}{R} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that creature.)

{R}: Paw Valley Wildclaw gets +1/+0 until end of turn. When this makes its power exactly 4, add {R}{R}{R}.

Target creature gets +2/+0 and gains lifelink until end of turn.

Flying
Whenever Haunting Horseman deals combat damage to a player, that player discards a card.

Destroy each creature with power 3 or greater.

Prevent all combat damage that would be dealt to you this turn. Populate. (Create a token that's a copy of a creature token you control.)

Pay 2 life: Lifecraft Aberration gains indestructible until end of turn.
Pay 3 life: Lifecraft Aberration gets +1/+1 until end of turn.

When Tumultuous Shrine enters or is put into a graveyard from the battlefield, up to one target land you control becomes a 4/4 Elemental creature with haste. It's still a land.

Choose one —
• Target creature gets +1/+0 and gains indestructible until end of turn.
• Tap target creature. Put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)
• Scry 1, then draw a card.

(As an Encounter enters, choose an opponent to protect it. You and others can attack it. When defense counters are removed, create a 0/0 Army token if you don't control one, then put that many +1/+1 counters on a Army you control.)
When Crisis in Danaj enters, return target creature an opponent controls to its owner's hand.

Equipped creature gets +2/+1 and has menace.
Whenever equipped creature deals combat damage to a player, they sacrifice two permanents.
Equip—{2}, Sacrifice a creature.

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Choose one —
• The next spell you cast this turn has flash and can't be countered.
• Target creature gets +2/+0 and gains haste until end of turn.
• Target creature gets +1/+0 and gains first strike until end of turn.

Rhapsody {3}{W}{W} (Pay {3}{W}{W} to cast this as a 4/4, or as a sorcery to make it become a 4/4.)
Lifelink

Instant and sorcery spells you cast cost {1} less to cast.

Menace
Whenever Searing Sandwurm is dealt damage, it deals that much damage to target player or planeswalker.